1. Field of the invention
The present invention relates to electric power conversion devices or power converters capable of converting direct current power to alternating current power.
2. Description of the Related Art
A general electric power conversion device has semiconductor modules, a capacitor, an input bus bar, a capacitor bus bar, etc. The semiconductor modules convert direct current power (DC power) to alternating current power (AC power). The capacitor smooths the electric power. The input bus bar is connected to a direct current power source (i.e. a DC power source). The capacitor is connected to the input bus bar through the capacitor bus bar. A patent document 1 as a conventional technique, Japanese patent laid open publication No. 2013-55840 uses a capacitor module having a structure in which the capacitor and the capacitor bus bar are assembled together and molded by resin. The capacitor bus bar is connected to a main bus bar. This main bus bar is connected to the semiconductor modules to supply an electric power to the semiconductor devices.
The electric power supplied through the main bus bar is further supplied to the input bus bar through the capacitor bus bar which is molded in the capacitor module.
However, the structure of the electric power conversion device disclosed by the patent document 1 previously described has a drawback. That is, because the electric power involving a direct current component (DC component) is supplied to the capacitor bus bar, the DC component of the electric power generates heat energy when the DC component of the electric power passes through the capacitor bus bar. In addition, because the capacitor bus bar is assembled to and molded in the capacitor module, the heat energy generated in the capacitor bus bar increases a temperature of the capacitor, and sometimes breaks the capacitor module. This causes deterioration of the capacitor module, and reduces the life time of the capacitor.